High speed physical secure key distribution in a classical optical fiber channel is unprecedentedly desired for modern secure communication, but it still remains a worldwide technical challenge. In this paper, we propose and experimentally demonstrate a novel high-speed physical secure key distribution scheme based on chaotic optical signal processing and private hardware modules, which employs chaotic self-carrier phase modulation for chaotic bandwidth expansion and time-delayed shift keying of commonly driven synchronized optical chaos for physical layer security. In this scheme, the entropy source rate of synchronized chaos output from two remote response lasers is greatly expanded by chaotic self-carrier delayed nonlinear phase disturbance, which facilitates high speed key extraction from the entropy source with guaranteed randomness. Moreover, a synchronization recovery time of sub-nanosecond is achieved by dynamic keying of the chaotic delay time after chaos synchronization to accelerate the key distribution rate. Based on the proposed scheme, a high physical key distribution rate of 2.1 Gb/s over 40 km is successfully demonstrated in the experiment. The proposed solution provides a promising strategy for future high-speed key distribution based on chaotic optical signal processing and classical fiber channel.

Chaotic optical communication based on conventional external cavity semiconductor laser is a very promising solution for physical layer secure communication. However, the intrinsic time delay signature (TDS) associated with the external cavity length and the potential direct linear filtering (DLF) or synchronization utilization attack greatly threaten the system security. In this work, we propose and numerically demonstrate a novel scheme for TDS suppression and security enhancement of chaotic optical communication based on external temporal self-feedback hardware encryption and decryption. In this scheme, the confidential chaotic modulated signal is temporally scrambled in the time domain by two optical dispersion components and an electro-optic self-feedback phase modulation loop between them, which simultaneously conceal the TDS and enhance the security against malicious attacks. Proof-of-principle demonstration for a security enhanced chaotic optical communication system with error free transmission is successfully achieved. The proposed scheme may provide a promising way for pure-hardware based physical secure chaotic optical communication systems.

We propose and experimentally demonstrate a novel, to the best of our knowledge, private correlated random bit generation (CRBG) scheme based on commonly driven induced synchronization of two wideband physical entropy sources, which employs an open-loop distributed feedback laser followed by a hybrid electro-optic nonlinear transformation hardware module for effective bandwidth expansion and privacy enhancement. A Mach–Zehnder interferometer followed by an electro-optic self-feedback phase modulation loop as well as a dispersion element are constructed as a private hardware module to perform post-processing and nonlinear transformation of the synchronized signal. A record high rate of 5.2-Gb/s CRBG is successfully achieved between two synchronized wideband physical entropy sources with an enhanced entropy source rate and hardware key space. The demonstrated scheme may provide a new way for CRBG in future high speed secure communication systems.

With the widespread application of big data, the amount of data transmitted through optical networks has been increasing dramatically. Correlated random bit generation (CRBG) is one of the key technologies in secure communication systems to ensure security performance and transmission efficiency. We propose and demonstrate a CRBG scheme based on a Mach–Zehnder modulator (MZM) electro-optic feedback loop to improve the security and speed of communication systems. In this scheme, common-signal-induced synchronization is accomplished to generate wideband complex physical entropy sources, and a private hardware module is employed to perform post-processing and nonlinear transformation of the synchronized signal. The simulation results show that the effective bandwidth of the output chaotic signal is significantly increased to 27.76 GHz, and high-quality synchronization with a correlation coefficient of over 0.98 is reached. A high-rate CRBG of up to 5.3 Gb/s is successfully achieved between two synchronized wideband physical entropy sources, and the hardware key space is enhanced to ∼242, which greatly improves the privacy of physical entropy sources. The proposed scheme provides a promising approach for high-speed private CRBG, which is expected to be used in high-speed secure key distribution and optical communication systems.

The application of artificial insemination is particularly, owing to which breeder animals are considered an important resource in breeding farms. However, the reproductive performance of roosters typically declines with age, and the economic loss experienced by breeders is attributable to this shortened reproductive lifespan. Lasia spinosa Thw. (LST) reportedly improved reproductive capacity in male rodents. The objective of this study was to investigate the effects of LST on the reproductive performance of aged roosters. Male Guangxi Partridge chicken (mean weight, 3032.41 ± 34.48 g; age, 500 days; n = 72) randomly received the following three dietary treatments: LST0 group (a basal diet), LST2 group (a basal diet with 2% LST powder), and LST4 group (a basal diet with 4% LST powder). Computer-aided sperm analysis revealed that dietary LST supplementation significantly improved semen volume, sperm motility, and concentration. Furthermore, the most potent effects were observed in the treatment group with the administration of 2% LST, which significantly improved the weight of the testes. Hematoxylin-eosin staining revealed the increase in diameter of the seminiferous tubule and height of the seminiferous tubule epithelium possibly caused as a result of LST treatment. A significant increase in fructose and glucose concentrations were observed in the testis and seminal plasma; in addition, a significant increase was observed in the α-glycosidase levels in the testis and spermatozoa. However, the monoaldehyde levels in the spermatozoa appeared to decline significantly. Additionally, the fertility rate increased significantly following 2% LST supplementation. RNA-seq analysis revealed that 34 and 16 unigenes were upregulated and downregulated, respectively, in testicular tissues from roosters that received dietary supplementation of 2% LST. The assigned functions of the unigenes revealed that LST primarily influenced the mechanisms underlying catalytic activity and cellular processes. Kyoto Encyclopedia of Genes and Genomes enrichment analysis suggested that spermatogenesis-related pathways were significantly enriched, including ABC transporters, ribosome biogenesis in eukaryotes, and VEGF, cAMP, and ErbB signaling pathways.